This invention relates to a connector comprising a signal contact for use in signal transmission and a ground contact connected to ground.
For example, an electrical connector of the type is disclosed in Japanese Patent (JP-B) No. 3564555 and Japanese Unexamined Patent Application Publication (JP-A) No. 2004-534358. The electrical connector is suitable for connection of lines transmitting high speed signals by a differential transmission method. In the transmission method, two signal lines (+, −) are used and “High” and “Low” of signals are discriminated by a potential difference between the two signal lines. Two signals transmitted through the two signal lines are equal in voltage level to each other and are different in phase from each other by 180°. In the transmission method, a noise produced in the two signal lines are canceled at an input stage of a receiver. Accordingly, a transmission accuracy is improved.
Referring to FIGS. 1A to 1E and 2, description will be made of an existing connector used in the differential transmission method.
The connector 21 comprises a plurality of signal contacts S, a plurality of ground contacts G, an insulating housing 22 holding the signal contacts S and the ground contacts G, and a shell covering the signal contacts S, the ground contacts G, and the housing 22. The shell 23 has a pair of spring portions 23a formed on its upper surface to be engaged with a mating connector.
The contacts S and G of the connector 21 has contacting portions C to be connected to respective contacts of the mating connector. The contacting portions C are arranged in two rows, i.e., upper and lower rows, as shown in FIG. 1B. The contacting portions of the contacts S and G are arranged in the order of S, S, G, . . . from the right side in the upper row and are arranged in the order of G, S, S, . . . from the right side in the lower row.
Referring to FIG. 2, the contacts S and G are similarly arranged in two rows, i.e., upper and lower rows in an upper part of the figure. Specifically, the contacts S, S adjacent to each other in the upper row and the contact G in the lower row are located at apexes of an isosceles triangle, respectively. Similarly, the contact G in the upper row and the contacts S, S adjacent to each other in the lower row are located at apexes of an isosceles triangle, respectively.
The contacts S and G have terminal portions T to be soldered and connected to a substrate. As shown in a lower part in FIG. 2, the terminal portions T are arranged in a single row at a predetermined pitch in the order of S, G, S, S, G, S, . . . from the right side.
However, as shown in FIG. 2, adjacent ones of the signal contacts S are close to each other at their intermediate portions Sm exposed out of the housing 22. Therefore, crosstalk easily occurs.